This invention relates to a high frequency heating appliance capable of defrosting frozen food, for example, through the use of high frequency energy, and more particularly to a high frequency heating appliance capable of defrosting chilled food under a state approximately equal to natural defrosting for a brief period of time due to a combination of heating performance of high frequency energy and the programming and controlling functions of a microcomputer.
High frequency heating appliances of the above described type whose sequence of heating is governed under a microcomputer are already on the market. Microcomputer-aided setting of the heating and cooking modes require the operator to actuate a selected one of the heating mode selection keys and a selected one of the heating period selection keys for determining the amount of high frequency output, that is, the heat output and heating time and thus requires a complex and inconvenient setting operation.
With the above described method, the operator must have a look at a cook book, an appendix of the high frequency heating appliance, and then determine the heating output and time in introducing heating output and time settings as well as the kind of food.
Generally speaking, when food is heated with high frequency energy, the phenomenon takes place wherein the surface of food tends to absorb a greater amount of high frequency energy and is heated more quickly than the central portion thereof. One of the conventional approaches to overcome the phenomenon is to defrost the food slowly with a low level (say, 240 W) of high frequency output or to set up a given period of standing shortly after the surface temperature of the food has reached a predetermined value and high frequency output has been interrupted, with the intention of alleviating and minimizing the difference between the surface and internal temperatures of the food (cf. FIG. 1).
The conventional method as stated above, however, requires a complicated actuating procedure and a substantial amount of time. Furthermore, though the degree of excessive or insufficient defrosting is different to some extent, there is still the undesirable phenomenon wherein the surface of the food is excessively defrosted but the central portion of the food is less defrosted. For example, chilled raw fish, cakes, etc. are hardly palatable even when being defrosted. It is further appreciated that the appearance of defrosted meet is too poor to stimulate appetite and does not encourage a cook to serve delicious and tasty food. When a cooking procedure is conducted subsequent to defrosting, the surface of the food is overheated but the central portion thereof is insufficiently heated. No better cooking is expected.